GWEN IFILL: Now to election 2012.
The key to the 270 electoral votes needed to win the presidency may lie at the base of the Rocky Mountains.
I traveled to Colorado recently to find out why.
Glenna Stewart moved back home to Jefferson County, Colo., earlier this year. She and her mother, Kristin, agree on most things, except this: Glenna plans to vote for Barack Obama, Kristin for Mitt Romney.
When I'm not standing here, do you guys ever talk about this stuff?
GLENNA STEWART, Colorado: Yes.
KRISTIN STEWART, Colorado: Yes.
KRISTIN STEWART: Usually heatedly and in the car.
GLENNA STEWART: We both have our positions.
KRISTIN STEWART: Well, we both agree on gay rights and the availability of abortions. And she thinks the government should take more of your money and spread it around. And I think the government should keep the hell off my money.
GWEN IFILL: We met the Stewarts at the annual Apple Cider Festival in the Denver suburb of Lakewood, much-valued voters both candidates need to win battleground Colorado.
The president deserves another chance, said 30-year-old Glenna.
GLENNA STEWART: I believe that he was dealt a very difficult hand, and in spite of a lot of the negative things that have happened, I think he's doing the very best that he can.
And I believe that he can continue to do good things for this country.
GWEN IFILL: But you like Romney?
KRISTIN STEWART: I like the Republican candidate -- the Republican point of view, shall we say. I like less government. I like less governmental interference in our lives.
GWEN IFILL: Colorado was once a reliably Republican state. No more. The mobile suburban voters in critical JeffersonCounty supported George W. Bush in 2000 and 2004, but then switched to Barack Obama in 2008.
So, in the campaign's final weeks, each candidate is trying to target those fickle voters again and again.
Jeffco, as the country is known, stretches more than 700 square miles along Denver's western edge. Three quarters of a million people live in the sprawling towns that hug the RockyMountain foothills, one-third of them Democrats, one-third Republican and one-third tied to neither party.
Maura Fletcher, mother of an 11-month-old, is part of that third category. She, too, spent part of her weekend at the festival, promoting the chiropractic business she and her husband run. She said she is embarrassed she hasn't yet made up her mind.
MAURA FLETCHER, Colorado: I'm not a political person. So I'm doing my research on what candidate will best support me as a female and me as a small business owner.
It's difficult making these decisions because some of the things Romney supports I don't think are conducive to women's issues. And, as a small business owner, I don't think that Obama is a good choice.
GWEN IFILL: Dick Wadhams, who ran the state Republican Party for years, says voters like Fletcher could hold the keys to the kingdom for Gov. Romney or President Obama.
DICK WADHAMS, former Colorado Republican chairman: There is something about those unaffiliated voters and even Republican women in those counties that are very elusive. They swing back and forth.
You cannot depend on them voting the same way in one election the way they did the previous election.
The Republican women I'm talking about are -- are basically fiscally conservative, economically conservative, but they are socially liberal.
And so what the Democrats try to do every election is flake off these Republican women with -- with social issues like abortion. And sometimes they succeed.
GWEN IFILL: Ten percent of the state's electorate lives in Jeffco, swing voters in a swing county in a swing state.
JUDY MERKEL, volunteer: If there were an election for president today, would you be voting for Barack Obama or Mitt Romney?
GWEN IFILL: Judy Merkel traipses from door to door on behalf of the Jefferson CountyRepublican Party. An active Tea Party volunteer focused on recruiting women, she spends her weekends on the hunt for the undecided and the unmotivated.
JUDY MERKEL: I think JeffersonCounty is a huge factor in this election because we have 118,000 independent women voters in JeffersonCounty and ArapahoeCounty who will help make -- make or break it. And as the counties go, the state will go.
GWEN IFILL: And what are the issues that they are drawn to?
JUDY MERKEL: This election is not about social issues. This election is critical for our economy. And I think we're engaging more and more of our independent voters to see that it's about our economy, it's about our jobs.
GWEN IFILL: Both candidates have become repeat visitors to JeffersonCounty, making direct appeals to swing voters.
MITT ROMNEY (R): I need you to commit to do something. I need you to each find at least one person who voted for Barack Obama last time and convince...
MITT ROMNEY: Oh, they're just fine. We need them to come vote for me this time.
So, we want -- I want you to find them and talk to them and ask them whether they can't vote in favor of someone who will bring real change and strengthen America again and bring back good jobs and rising incomes.
And I will do it. I need your help to do it because this is the state that could decide it.
PRESIDENT BARACK OBAMA: I have got to say, Colorado, after all we have been through, the idea that we would roll back regulations that we finally put in place on Wall Street to make sure they don't act recklessly again and bring the economy back to its knees.
I don't think rolling back regulations on Wall Street are going to help the small businesswoman in JeffersonCounty.
GWEN IFILL: On the stage with President Obama in Golden last month was campaign volunteer Lisa Cillessen, a local teacher. Lisa and her husband, Jeremiah, the parents of three children, with another on the way, say they are even more pro-Obama than four years ago.
LISA CILLESSEN, Colorado: What changed for me was when I actually started working on the campaign and really, really started digging into some of the things that have been accomplished in the past four years.
This is still the right leader for our country, and we still need to keep moving this direction.
GWEN IFILL: Jeremiah is a classic Jeffco voter, a registered Republican who is crossing party lines to support Mr. Obama. But he also believes the president fell short in last week's debate.
JEREMIAH CILLESSEN, Colorado: I think he really has to lock in on the undecided voters, and that's where it's going to be won, particularly in this county. And I think there is an overwhelming number who after the first debate shifted a little bit.
They're looking for somebody they can trust and somebody they can believe in. And in the first debate, Romney appeared to be that candidate.
MAN: We have to get to these doors. This is the difference between winning and losing.
GWEN IFILL: Both campaigns are stepping up their games. Republican volunteers crowded into this weekend phone bank after the first debate.
When you talk to voters after the debate, are people saying, well, OK, I'm giving him a second look?
JUDY MERKEL: Yes, definitely, definitely. The majority of them I'm speaking to are saying, hey, we see what you have been seeing. We're on. We're on with you, girl. So that's great.
GWEN IFILL: Even the undecided Maura Fletcher said she was impressed by Romney's performance.
MAURA FLETCHER: He's polished. He answers the questions succinctly. What he said made sense to me.
GWEN IFILL: Chris Kennedy, who runs the Jefferson County Democratic Party, organized a local candidates chili cook-off this past weekend. He conceded the debate may have made his job more difficult.
CHRIS KENNEDY, Jefferson County, Colo., Democratic Party: There were probably a few unaffiliateds who went Romney's way after that. I'm not going to lie.
But we have the stronger campaign on the ground. And I think President Obama has got a stronger message that resonates with more people. And I think that's going to come -- it's going to bring us to the top in the end.
GWEN IFILL: The president's fortunes could shape the outcome for local candidates like Democrat Evie Hudak, who is seeking her second term in the state Senate.
STATE SEN. EVIE HUDAK (D-Colo.): If you look at the performance in my district, you will see that, for example, the Democrat will win for one seat and the Republican will win for another seat. So it's very hard to predict which of the Democrats and which of the Republicans who are going to win.
GWEN IFILL: Four years ago you won, but by how much?
EVIE HUDAK: Well, I won by 2 percent, which was a huge margin of victory for a Democrat in my district.
MAN: I'm calling from the Colorado Republican Party.
GWEN IFILL: An additional complication: The election could well be over before Election Day arrives. Pollsters say up to 95 percent of voters have already made up their minds.
MAN: Thanks so much, Steve.
GWEN IFILL: And as early voting begins in Colorado Monday, 70 percent of the state's voters have already signed up to vote by mail.
WOMAN: Thank you.
GWEN IFILL: You can watch a photo collage of more of those Colorado campaign workers hard at work on our Tumblr page at NewsHour.Tumblr.com.